GB312046A - Improvements in and relating to the manufacture of concentrated acetic acid - Google Patents

Abstract

312,046. Distilleries des Deux-SÞvres. May 19, 1928, [Convention date]. Acetic acid is extracted from its aqueous solutions by solvents sparingly soluble in water and having a boiling point which may be close to or identical with that of acetic acid, the resultant extract being distilled in a continuous manner with an entraining liquid capable of forming a binary azeotropic mixture both with acetic acid and with water, the boiling point of the latter mixture being the lower. For example, 30 per cent acetic acid is extracted with butyl acetate. forming a solution containing 16 per cent acetic acid and 5.5 per cent water. This is introduced by a pipe 2 into a column 1 containing the requisite quantity of a petroleum fraction boiling between 99 and 101‹ C. A binary mixture of water and petroleum boiling at 80‹ C. passes up into a condenser 4 and thence to a separator 5 from which the petroleum layer is returned by a pipe 7. A binary mixture of acetic acid and petroleum boiling at 94‹ C. passes out at 8 through a condenser 9 to a separator 10, from which the petroleum layer is returned by a pipe 11. The lower layer of 90-99 per cent acetic acid is passed to a column 13 containing petroleum; the final traces of water are distilled off as petroleum-water mixture to a condenser 15 and a separator 16. Part of the water is returned by a pipe 18 to prevent the rise. of acetic acid in the column 13, and the remainder by a pipe 17 to a column 1. The petroleum is returned by pipes 19, 20 to columns 13, 1 respectively. Anhydrous acetic acid is withdrawn from pipe 14, and butyl acetate from the bottom of the column 1.